Plasticity and fracture properties of laser powder bed fusion fabricated 316L stainless steel - Experimental and numerical investigations

To understand the complex mechanical behaviour of Laser Powder Bed Fusion (LPBF) fabricated 316L stainless steel (LPBF-316L), its anisotropic plasticity and ductile fracture are systematically investigated under various stress states and strain rates in this study. For comparison, tensile tests are also conducted on traditionally rolled 316L stainless steel (TR-316L) samples. Based on the experimental results, the transversely isotropic Hill-48 yield criterion and a modified Johnson-Cook (J-C) plasticity model are calibrated to describe the dynamic and anisotropic plastic response. Scanning electron microscopy reveals that fracture morphology is strongly influenced by stress state, strain rate, and build orientation, with void coalescence and dimple formation indicative of ductile failure, alongside manufacturing-induced defects. Additionally, a modified Mohr-Coulomb criterion (MMC) is proposed to characterise both anisotropic fracture initiation and strain rate sensitivity. A combination of experimental and numerical approaches is employed to capture the evolution of stress and strain fields during deformation. Finally, a comparative analysis of the three-dimensional fracture envelopes of TR-316L and LPBF-316L samples is performed. It is found that LPBF-316L exhibits lower sensitivity to the average normalised Lode angle than TR-316L. This study offers critical insight into the mechanical performance of additively manufactured metallic materials and informs the development of predictive models for advanced structural applications. • Quasi-static and dynamic tensile tests are conducted for TR-316L and LPBF-316L specimens. • Plastic and fracture behaviour are assessed under various stress states and strain rates. • Hill-48 yield criterion, modified J-C model and damage evolution law are proposed. • MMC criterion is modified to describe the strain rate and orientation dependent fracture initiation. • 3D fracture envelope of TR-316L and LPBF-316L are comparatively analysed.